Simplified integrating motor



31 D -1 1 SR FZ P85 (1 2 KR 5 $53? A 921.

Nov. 10, 1970 'r. A.COHEN 3,539,921

I SIMPLIFIED INTEGRATING MOTOR Filed Nov. 6, 1967 COUNTER COUNTER 3/ 33 r" soFT MAGNETIC MATERIAL k 7 37 EXCITATION? c 357 A g ouTPuT COUNTER FIG-3.2

INVENTORS:

HUGH E. RIORDAN Y THEODORE A .COHEN B ATTO EY 3,530,923 SIMPLIFIED INTEGRATHNG METER Theodore A. Cohen, Bronx, N.Y., and Hugh E. Riordan, Wycbofl, Ni, assignors to Singer-General Precision,

Koo, Little Falls, NE, a corporation of Delaware Filed Nov. 6, 1967, Ser. No. 680,866

lint. Cl. H03lt 13/00; @GZid 7/02; Gilli" 19/26 U3. Ql. 32%93 Claims N... to

ABSTRAQT OF THE DESCIJOSIJRE BACKGROUND OF THE INVENTION Field of the invention The present invention relates to an integrator, and more particularly to an integrator which supplies a digital output in the form of a pulse count.

Description of the prior art In many data processing systems, including inertial guidance, navigation and control systems, it is necessary to obtain the precise time integral of an electrical DC.

voltage. Such a voltage may represent the output of a gyroscope, accelerometer or other sensing instrument, or the outputof a computing device or signal generator. The most precise method of time integration consists of count ing a series of pulses or signal alternations, when the frequency of the pulses or alternations is proportional to the quantity (e.g., voltage) to be integrated.

in addition, a signal containing information in the form of suppressed carrier frequency modulation is easily ac cepted by most types of digital computer.

Therefore, devices capable of precisely converting a voltage into a pulse train or other cyclical form in which the frequency is equal to the product of a constant by the applied voltages are in constant demand.

Trcviously, such devices have been either relatively inaccurate or excessively expensive and complicated. For example, a fined field DC. motor having a non-magnetic rotating armature will run at a speed which is closely proportional to the applied voltage. If a photoelectric,

magnetic or other type of pulse or A.C. signal generator is coupled to the motor shaft, the frequency of the output signal will be proportional to the motor speed and hence to the voltage applied to the motor. The magnitude of the deviation from perfectly linear proportionality depends on the size and stability of the following parameters or effects: 1

.'lhese effects. can be reduced by careful design andv construction, but even with the greatest care the sum of these errors-will amount to 0.5% to 1% referred to full scale. The friction alone contributes an error of 0.25%

of full scale. For critical applications, a total error of-' 3,539,921 Patented Nov. 10,1970

SUMMARY OF THE INVENTION Generally speaking the integrator of the present invention comprises a toroidal container filled with a conducting fluid, e.g., mercury with a bead of non-conducting material therein. The toroidal container is disposed so that one portion thereof is in a magnetic .field and a DC. current is passed across the toroidal container at right angles to the magnetic field. This will cause the liquid and bead to flow around the toroid at a velocity corresponding approximately to the voltage drop between electrodes. Sensing means detect each time the bead passes before a sensing station. The number of times the bead rotates around during a time interval is a digital count of the applied voltage over the time interval.

The invention as well as other objects and advantages thereof will become apparent from the following description taken in conjunction with the accompanying drawing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING FIG. 1 is a perspective view of the integrator herein contemplated;

FIG. 1A is a crosssectional view along lines 1A--1A of FIG. 1; and

FIG. 2 is a cross sectional view of a modified form of the integrator shown in FIG. 1.

DETAILED DESCRIPTION Shown in FIG. 1 is a toroidal container 11 filled with a conducting fluid l3, e.g., mercury or sodium-potassium alloy. A portion 15 of toroidal container lll is placed between the north and south poles 17 and 19 of magnet 21. Electrodes 23 and 25are disposed at right angles to the magnetic field B at opposite sides of container 11. Within the container 11 is a bead 27 made of non-con ducting material of a density closely approximating that of the liquid. Disposed at various stations around the container ll are sensing electrodes 29, and/or photocells 30. When a toroidal container filled with a conducting liquid such as mercury or sodiumpotassium alloy, is crossed by a magnetic field in the vicinity of a pair of conducting electrodes as shown in FIG. 1, a current passed between the electrodes through the liquid will cause the liquid to fiow around the torus with an average velocity closely related to the voltage drop between the electrodes. The output of the sensing electrodes 29 and/or photocells 30 are counted in counters 32 and 34. The relation between average velocity of the liquid and the applied voltage may be made as nearly linear as is desired by careful design of the fluid path, the magnetic circuit and the electrodes. With the bead of non-conducting material of a density closely approximating that of the liquid, placed in the toroidal container, the speed of the liquid flow may be determined by measuring the number of times the bead passes a fixed point per unit time. The total count of passages is thus the time integral of the speed and hence proportional to the time integral of the applied voltage. The passage of the bead may be sensed by placing one or more pairs of electrodes around the toroidal container as shown in FIG. 1 and sensing the change of resistance between theelectrodcs as thc oi an as shown F46. Shown in PEG. 2 is a cross sectional view of the excitation and p c off arrangement.

Container Ill; with the liquid 33 and i came as in FIG. 1. The magnet 33. is of the go type having an excitation coil and an output co; J5 wound on the center leg. Each time the head 27 passes before the magnet, 22 change in impedance will take across output coil to a counter it to be observed therefore that the present invennrovides for a. toroidal container ll disposed in n 1 E in h. a conducting fiuid having a head 2') of non-conducting material therein; a magnetic generator 2?. is disposed so as to create a magnetic field ht angles to said defined plane. Sensing means 25"" are disposed at a sensing station next to the toroidal container which are adapted to sense the possage of head 27 past the station. The number of times the bend rotates around the toroidal container past the stallion during a time interval is a digital count of the applied voltage over said time interval. The field gem orator may be n horseshoe magnet 21 with inwardly facing oles l7 and it) disposed so that the pole faces lie parallel to the defined plane, the magnetic ficld thus passing between poles at right angles to the defined plane. The sensing means may be sensing electrodes 29 passing smai current across the toroidal container which is interrupted by the passage of the bead 27 and counter means 3 6 coupled to the sensing electrodes counting the times the current has been so interrupted; or, the sensing means nary be a photocell providing an output wh n light flowing thereto is interrupted by the passage of bead and counter means coupled to said photocell. counting the number of such interruptions. The sensing means and magnetic field generator may be combined as it ge having an excitation coil and lit output Wound around the center leg the-.c f with counter rncsns couple to the output coil counting the c-nngcs dance across the output coil, each time the bead tnrretl cnibr. s, it will he obvious to thos the art that var ,us modifications ckn be m tit: scope of the invention, and is intc it.

nded claim cover all such modifications. s claimed is:

arr-.tns for ohtnir 'oltngc corn u toroidal container disposed in a defin d "ving a conducting; fluid cl.

fluid including head i rgtemtl; a. magnetic field gencrettw .o said container so as to crw at right angles to said defined plane; and a of electrodes coupled acrossisaid toroidal concr in the vicinity of said magnetic field generator reby said conducting fluid will be caused to fiow ound the torus defined by said container in reonsc to said applied voltage being impressed across pair of electrodes; said apparatus further innding sensing means disposed at a. sensing station acent to the toroidal container for detecting the M sage of said head past said station, and counter means responsive to said sensing means for recording the number of times said bead rotates around said toroidal container past said station during a predetermined time interval whereby the output of said counter means is proportional to the integral of the applied voltage over said predetermined time interval.

The apparatus claimed in claim ll, said magnetic generator being a horseshoe magnet with inwardly fusing poles disposed so that the pole faces lie parallel said defined plane, the magnetic field passing between poles at right angles to said defined plane.

Apparatus as claimed in claim 1 wherein said sensmeans comprises a pair of spaced electrodes for nnssing a small current across said toroidal container hich current is interrupted by the passage of said bead, said counter means being responsively coupled to said spaced electrodes for counting the times the current has been so interrupted.

d. The apparatus as claimed in claim 1 wherein said sensing means includes at least one photocell for pro-- viding an output when light flowing thereto is interrupted by the passage of said bead, said counter means being rcsponsivcly coupled to said photocell for counting the number of such interruptions. 1

5. The apparatus as claimed in claim 1 wherein said sensing means and said magnetic field generator are comblood in the form of an E-bridge pick off having an excitation coil and an output coil Wound around the center leg thereof said counter being responsively coupled said output coil for counting the changes in impedance the output coil each time said bead passes said sensing station.

" etercnccs Qitcd .YNAlD R. WXLEUR, Primary Examiner rHESZ, 521., Assistant Examiner 

